1. Field of the Invention
The present invention relates generally to a forward converter and more particularly, to a voltage stabilizer circuit of forward converter that uses the power switch as voltage stabilizing and current rectifying member to achieve synchronous rectification of current and increasing of frequency response.
2. Description of the Related Art
FIG. 1 is a circuit block diagram of a conventional forward converter. According to this design, the forward converter comprises a voltage stabilizer 100, a rectifier 110, an error amplifier 121, and a control circuit 130. The voltage stabilizer 100 comprises a saturated magnetic amplifier 101 and a rectifier 102. This structure of forward converter has numerous drawbacks as follows: (1) It needs to control the magnetized current of the saturated magnetic amplifier 101 so as to regulate the pulse width of the transformer winding. (2) The voltage stabilizer 100 has two elements, namely, the saturated magnetic amplifier 101 and the rectifier 102 that are necessary for controlling its output voltage. (3) For rectifying current synchronously, a metal oxide semiconductor field effect transistor shall be used to substitute for the rectifier 102, and an additional control circuit is needed. (4) The frequency response of the rectifier 110 is relatively low, and for the sake of cost, the frequency response of the rectifier 110 may be designed below 200 KHz.
Therefore, it is desirable to provide a voltage stabilizer circuit of forward converter that eliminates the aforesaid drawbacks.